1.Field of the Invention
The present invention is directed to a method and arrangement for automatic modem type recognition and adaptation
2.Description of the Prior Art
U.S. Pat. No. 3,255,439 discloses an apparatus for secure recrediting of a postage meter machine with a monetary balance that was already supplied with an automatic signal transmission, via data transmission equipment including a converter, from the postage meter machine to the central data installation, whenever a predetermined franked monetary amount, or a predetermined number of processed pieces of mail, or a predetermined period of time, was reached. Alternatively, a signal corresponding to the monetary amount, piece number or time period can be transmitted. The communication ensues by means of binary signals via converters connected with one another via a telephone line. The machine receives a likewise secured recrediting corresponding to the credit balance, and reverts to a locked condition if no credit is subsequently supplied. The fact that this known apparatus us limited to the sue of special converters for the signal transmission is disadvantageous.
A configurable interface for a postage meter machine is known from European Application 285 390. A modem is selectively controlled by the interface in order to transmit data between the postage meter machine and an apparatus, Not only secured data, but unsecured data as well, are to be transmitted between apparatuses. Since different special interfaces would be burdensome in a postage meter machine, and a new communication standard would not be able to be implemented without unavoidable delays, a general purpose communication port was provided.
A postage meter machine known from European Application 660 269 is equipped with at least one input means, an output means, an I/O control module, a memory device that contains the program register, data register, and in particular the accounting register, a control device, a printer module and a modem. The modem is a special data transmission apparatus for telephone networks. It is disadvantageous that only a predetermined modem type coupled to a particular interface is used. Variant postage meter machines are also commercially available with manual recrediting at the post office, which are however prepared for future connection with a central data station via a predetermined modem type. It is not acceptable to the user or lessee if it later turns out that the required type is no longer available or allowed. A subsequent reprogramming would have to be carried out using a reset EPROM, which is complicated and costly.
At present, there exists a constant increase in the demands made on a modem used in postage meter machines is to be noted. During each communication with the remote central data station, it is generally known to transmit the identity number of the postage meter machine and the values in the postal registers to the central data station for authorization before a recrediting a credit account. It has also been proposed that when a predetermined piece number of postage meter impressions is reached, a communication with the remote central data station is automatically initiated in order to recredit a piece number. In the future, modems with higher transmission rates will be available that allow the economical transmission of larger quantities of data. Modems used in postage meter machines will vary according to the different transmission rate requirements. Correspondingly, a program adaptation of the program stored in the postage meter machine would have to be carried out according to modem type, or according to whether a low-cost variant or a "luxury" security variant of the postage meter machine is used. On the other hand, no other modem type is usable even in case of repair, particularly if the program cannot be subsequently altered. The country-specific telephone apparatus likewise includes special technical features that are to be taken into account before a data communication takes place.
For electronic apparatuses, terminals or postage meter machines that are to be communicatively connected with remote data processing devices or other electronic unit, it is often desired that different types can also be built into or externally connected to special data transmission devices for telephone networks. In this area, a rapid development in modems is taking place, so that some modem types rapidly become obsolete and are no longer obtainable, or are no longer usable. Disadvantages include, e.g. for the different modem types, a highly fluctuating transmission rate and the different control sequences for the connection setup after a communication, or for connection dismantling after a communication. It is true that the connection protocol that occurs after a connection setup is largely standardized, and corresponds to the postal regulations in force and/or international recommendations in force. For each country there exist different regulations for the connection of telecommunication terminal equipment to the respective postal network. In contrast to the remote data processing installation or central data station, where a modem type can be used that can recognize and process the different connection protocol types, the required changes and modifications are more often necessary in the manufactured terminal equipment. In the manufacturing of electronic terminals, a large number of different modem types is used. Such terminals are to be used in various countries after being manufactured. Thus, a country-specific modem type adaptation and initialization must be undertaken each time, if a communication to the respective remote data processing device is to take place during later country-specific use. The retrofitting of an existing terminal with an external modem that is to be coupled with the existing interface thus cannot be carried out by the customer himself. Such a retrofitting with an external modem is particularly advantageous for postage meter machines that contain stored monetary data subject to consumption which must be replenished at time intervals.